1. Field of the Invention
The present invention relates to an artificial spinal facet joint or prosthesis to replace a diseased, damaged, or otherwise painful facet joint.
2. Description of the Prior Art
This invention relates to an artificial facet joint comprised of two components, a superior articular component and an inferior articular component. The superior articular components is designed to replace the articular surface of the inferior articular process and the inferior articular component is designed to replace the articular surface of the superior articular process.
The function of the facet joint is to guide vertebral motion and to resist compression, rotation and shear. The facet joints share in supporting an estimated 10-15% of the load of the lumbar spine. The load upon the facets increases with extension of the spine. A large body of evidence exists to support the fact that the facet joint is a pain producing structure. This pain can be disabling to some degree in some people. This pain can be due to trauma to and/or degeneration of the facet joint.
An artificial facet joint should cover the articular surfaces of the painful facet joint. It should aid in guiding vertebral motion and be able to withstand compression, rotation and shear force. It should not cause compression to adjacent neural structures. The artificial facet joint should be both biocompatible and biostable so that the joint itself and its degradation by-products, if any exist, should not cause adverse tissue reactions.
It is a principal objective of this invention to provide an artificial facet joint that has these characteristics.